To protect the Superfortress, Boeing designed the most sophisticated remote-controlled, defensive weapons system yet fitted to a military airplane. Engineers placed five gun turrets on the fuselage: a turret above and behind the cockpit that housed two .50 caliber machine guns (four guns in later versions), and another turret aft near the vertical tail equipped with two machine guns; plus two more turrets beneath the fuselage, each equipped with two .50 caliber guns. One of these turrets fired from behind the nose gear and the other hung further back near the tail. Another two .50 caliber machine guns and a 20-mm cannon (in early versions of the B-29) were fitted in the tail beneath the rudder. The really novel innovation was in the sighting system. Gunners operated these turrets by remote control. They aimed the guns using computerized sights, and each gunner could take control of two or more turrets to concentrate firepower on a single target, making the system flexible and effective.
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